Updated UI with accounts and fixed routing

ui/src/components/Administration.tsx

@@ -0,0 +1,18 @@
+import { Header } from '@components/Header';
+import { Navigate } from 'react-router';
+import { useUserContext } from '@components/context/UserContext.tsx';
+
+export function Administration() {
+  const { user } = useUserContext();
+
+  if (user == undefined) {
+    return <Navigate to={'/'} />;
+  }
+
+  return (
+    <>
+      <Header />
+      Todo: administration {user?.email}
+    </>
+  );
+}